/*
 *------------------------------------------------------------------
 * af_packet.c - linux kernel packet interface
 *
 * Copyright (c) 2016 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *------------------------------------------------------------------
 */

#include <linux/if_packet.h>

#include <vlib/vlib.h>
#include <vlib/unix/unix.h>
#include <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>

#include <vnet/devices/af_packet/af_packet.h>

#define foreach_af_packet_input_error

typedef enum {
#define _(f,s) AF_PACKET_INPUT_ERROR_##f,
  foreach_af_packet_input_error
#undef _
  AF_PACKET_INPUT_N_ERROR,
} af_packet_input_error_t;

static char * af_packet_input_error_strings[] = {
#define _(n,s) s,
    foreach_af_packet_input_error
#undef _
};

enum {
  AF_PACKET_INPUT_NEXT_DROP,
  AF_PACKET_INPUT_NEXT_ETHERNET_INPUT,
  AF_PACKET_INPUT_N_NEXT,
};

typedef struct {
  u32 next_index;
  u32 hw_if_index;
  int block;
  struct tpacket2_hdr tph;
} af_packet_input_trace_t;

static u8 * format_af_packet_input_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  af_packet_input_trace_t * t = va_arg (*args, af_packet_input_trace_t *);
  uword indent = format_get_indent (s);

  s = format (s, "af_packet: hw_if_index %d next-index %d",
	      t->hw_if_index, t->next_index);

  s = format (s, "\n%Utpacket2_hdr:\n%Ustatus 0x%x len %u snaplen %u mac %u net %u"
	      "\n%Usec 0x%x nsec 0x%x vlan_tci %u"
#ifdef TP_STATUS_VLAN_TPID_VALID
	      " vlan_tpid %u"
#endif
	      ,
	      format_white_space, indent + 2,
	      format_white_space, indent + 4,
	      t->tph.tp_status,
	      t->tph.tp_len,
	      t->tph.tp_snaplen,
	      t->tph.tp_mac,
	      t->tph.tp_net,
	      format_white_space, indent + 4,
	      t->tph.tp_sec,
	      t->tph.tp_nsec,
	      t->tph.tp_vlan_tci,
#ifdef TP_STATUS_VLAN_TPID_VALID
	      t->tph.tp_vlan_tpid,
#endif
	      t->tph.tp_net);
  return s;
}

always_inline void
buffer_add_to_chain(vlib_main_t *vm, u32 bi, u32 first_bi, u32 prev_bi)
{
  vlib_buffer_t * b = vlib_get_buffer (vm, bi);
  vlib_buffer_t * first_b = vlib_get_buffer (vm, first_bi);
  vlib_buffer_t * prev_b = vlib_get_buffer (vm, prev_bi);

  /* update first buffer */
  first_b->total_length_not_including_first_buffer +=  b->current_length;

  /* update previous buffer */
  prev_b->next_buffer = bi;
  prev_b->flags |= VLIB_BUFFER_NEXT_PRESENT;

  /* update current buffer */
  b->next_buffer = 0;

#if DPDK > 0
  struct rte_mbuf * mbuf = rte_mbuf_from_vlib_buffer(b);
  struct rte_mbuf * first_mbuf = rte_mbuf_from_vlib_buffer(first_b);
  struct rte_mbuf * prev_mbuf = rte_mbuf_from_vlib_buffer(prev_b);
  first_mbuf->nb_segs++;
  prev_mbuf->next = mbuf;
  mbuf->data_len = b->current_length;
  mbuf->data_off = RTE_PKTMBUF_HEADROOM + b->current_data;
  mbuf->next = 0;
#endif
}

always_inline uword
af_packet_device_input_fn  (vlib_main_t * vm, vlib_node_runtime_t * node,
			    vlib_frame_t * frame, u32 device_idx)
{
  af_packet_main_t * apm = &af_packet_main;
  af_packet_if_t * apif = pool_elt_at_index(apm->interfaces, device_idx);
  struct tpacket2_hdr *tph;
  u32 next_index = AF_PACKET_INPUT_NEXT_ETHERNET_INPUT;
  u32 block = 0;
  u32 rx_frame;
  u32 n_free_bufs;
  u32 n_rx_packets = 0;
  u32 n_rx_bytes = 0;
  u32 * to_next = 0;
  u32 block_size = apif->rx_req->tp_block_size;
  u32 frame_size = apif->rx_req->tp_frame_size;
  u32 frame_num = apif->rx_req->tp_frame_nr;
  u8 * block_start = apif->rx_ring + block * block_size;
  uword n_trace = vlib_get_trace_count (vm, node);
  u32 n_buffer_bytes = vlib_buffer_free_list_buffer_size (vm,
    VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX);
  u32 min_bufs = apif->rx_req->tp_frame_size / n_buffer_bytes;

  if (apif->per_interface_next_index != ~0)
      next_index = apif->per_interface_next_index;

  n_free_bufs = vec_len (apm->rx_buffers);
  if (PREDICT_FALSE(n_free_bufs < VLIB_FRAME_SIZE))
    {
      vec_validate(apm->rx_buffers, VLIB_FRAME_SIZE + n_free_bufs - 1);
      n_free_bufs += vlib_buffer_alloc(vm, &apm->rx_buffers[n_free_bufs], VLIB_FRAME_SIZE);
      _vec_len (apm->rx_buffers) = n_free_bufs;
    }

  rx_frame = apif->next_rx_frame;
  tph = (struct tpacket2_hdr *) (block_start + rx_frame * frame_size);
  while ((tph->tp_status & TP_STATUS_USER) && (n_free_bufs > min_bufs))
    {
      vlib_buffer_t * b0, * first_b0 = 0;
      u32 next0 = next_index;

      u32 n_left_to_next;
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
      while ((tph->tp_status & TP_STATUS_USER) && (n_free_bufs > min_bufs) &&
	     n_left_to_next)
	{
	  u32 data_len = tph->tp_snaplen;
	  u32 offset = 0;
	  u32 bi0 = 0, first_bi0 = 0, prev_bi0;

	  while (data_len)
	    {
	      /* grab free buffer */
	      u32 last_empty_buffer = vec_len (apm->rx_buffers) - 1;
	      prev_bi0 = bi0;
	      bi0 = apm->rx_buffers[last_empty_buffer];
	      b0 = vlib_get_buffer (vm, bi0);
	      _vec_len (apm->rx_buffers) = last_empty_buffer;
	      n_free_bufs--;

	      /* copy data */
	      u32 bytes_to_copy = data_len > n_buffer_bytes ? n_buffer_bytes : data_len;
	      b0->current_data = 0;
	      clib_memcpy (vlib_buffer_get_current (b0), (u8 *) tph + tph->tp_mac + offset, bytes_to_copy);

	      /* fill buffer header */
	      b0->clone_count = 0;
	      b0->current_length = bytes_to_copy;

	      if (offset == 0)
		{
#if DPDK > 0
		  struct rte_mbuf * mb = rte_mbuf_from_vlib_buffer(b0);
		  rte_pktmbuf_data_len (mb) = b0->current_length;
		  rte_pktmbuf_pkt_len (mb) = b0->current_length;
#endif
		  b0->total_length_not_including_first_buffer = 0;
		  b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
		  vnet_buffer(b0)->sw_if_index[VLIB_RX] = apif->sw_if_index;
		  vnet_buffer(b0)->sw_if_index[VLIB_TX] = (u32)~0;
		  first_bi0 = bi0;
		  first_b0 = vlib_get_buffer(vm, first_bi0);
		}
	      else
		buffer_add_to_chain(vm, bi0, first_bi0, prev_bi0);

	      offset += bytes_to_copy;
	      data_len -= bytes_to_copy;
	    }
	  n_rx_packets++;
	  n_rx_bytes += tph->tp_snaplen;
	  to_next[0] = first_bi0;
	  to_next += 1;
	  n_left_to_next--;

	  /* trace */
	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT(first_b0);
	  if (PREDICT_FALSE(n_trace > 0))
	    {
	      af_packet_input_trace_t *tr;
	      vlib_trace_buffer (vm, node, next0, first_b0, /* follow_chain */ 0);
	      vlib_set_trace_count (vm, node, --n_trace);
	      tr = vlib_add_trace (vm, node, first_b0, sizeof (*tr));
	      tr->next_index = next0;
	      tr->hw_if_index = apif->hw_if_index;
	      clib_memcpy(&tr->tph, tph, sizeof(struct tpacket2_hdr));
	    }
	  /* enque and take next packet */
	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
					   n_left_to_next, first_bi0, next0);

	   /* next packet */
	  tph->tp_status = TP_STATUS_KERNEL;
	  rx_frame = (rx_frame + 1) % frame_num;
	  tph = (struct tpacket2_hdr *) (block_start + rx_frame * frame_size);
	}

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  apif->next_rx_frame = rx_frame;

  vlib_increment_combined_counter
    (vnet_get_main()->interface_main.combined_sw_if_counters
     + VNET_INTERFACE_COUNTER_RX,
     os_get_cpu_number(),
     apif->hw_if_index,
     n_rx_packets, n_rx_bytes);

  return n_rx_packets;
}

static uword
af_packet_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
		    vlib_frame_t * frame)
{
  int i;
  u32 n_rx_packets = 0;

  af_packet_main_t * apm = &af_packet_main;

  clib_bitmap_foreach (i, apm->pending_input_bitmap,
    ({
      clib_bitmap_set (apm->pending_input_bitmap, i, 0);
      n_rx_packets += af_packet_device_input_fn(vm, node, frame, i);
    }));

  return n_rx_packets;
}

VLIB_REGISTER_NODE (af_packet_input_node) = {
  .function = af_packet_input_fn,
  .name = "af-packet-input",
  .format_trace = format_af_packet_input_trace,
  .type = VLIB_NODE_TYPE_INPUT,
  .state = VLIB_NODE_STATE_INTERRUPT,
  .n_errors = AF_PACKET_INPUT_N_ERROR,
  .error_strings = af_packet_input_error_strings,

  .n_next_nodes = AF_PACKET_INPUT_N_NEXT,
  .next_nodes = {
    [AF_PACKET_INPUT_NEXT_DROP] = "error-drop",
    [AF_PACKET_INPUT_NEXT_ETHERNET_INPUT] = "ethernet-input",
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (af_packet_input_node, af_packet_input_fn)